Effects of head-elevated position on tracheal intubation using a McGrath MAC videolaryngoscope in patients with a simulated difficult airway: a prospective randomized crossover study

Table 4 Carryover and period effects

	Sequence 1^a (n = 32)	Sequence 2^b (n = 32)	Difference (95% CI)	P value
POGO score, %
Sequence effect^c	102.3 ± 52.1	91.4 ± 33.4	10.9 (−11.0 to 32.9)	0.32
Period effect^d	16.4 ± 16.3	27.3 ± 20.4	−10.9 (−20.2 to − 1.7)	0.02

Data are presented as the mean ± standard deviation. ^aSequence 1: head-elevated position, followed by head-flat position. ^bSequence 2: head-flat position, followed by head-elevated position. ^cSequence effect: sum of POGO scores in the first position (period 1) and second position (period 2). ^dPeriod effect: difference between POGO scores in the head-elevated and head-flat positions (head-elevated minus head-flat). CI Confidence interval, POGO Percentage of glottic opening

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